Safya Belghith

Bio: Safya Belghith is an academic researcher from Tunis University. The author has contributed to research in topics: Encryption & Chaotic. The author has an hindex of 30, co-authored 173 publications receiving 3087 citations. Previous affiliations of Safya Belghith include École Normale Supérieure.

OCML-based colour image encryption

Abstract: The chaos-based cryptographic algorithms have suggested some new ways to develop efficient image-encryption schemes. While most of these schemes are based on low-dimensional chaotic maps, it has been proposed recently to use high-dimensional chaos namely spatiotemporal chaos, which is modelled by one-way coupled-map lattices (OCML). Owing to their hyperchaotic behaviour, such systems are assumed to enhance the cryptosystem security. In this paper, we propose an OCML-based colour image encryption scheme with a stream cipher structure. We use a 192-bit-long external key to generate the initial conditions and the parameters of the OCML. We have made several tests to check the security of the proposed cryptosystem namely, statistical tests including histogram analysis, calculus of the correlation coefficients of adjacent pixels, security test against differential attack including calculus of the number of pixel change rate (NPCR) and unified average changing intensity (UACI), and entropy calculus. The cryptosystem speed is analyzed and tested as well.

Efficient cryptosystem approaches: S-boxes and permutation–substitution-based encryption

Abstract: In this paper, two efficient cryptosystem schemes in the form of permutation–substitution based on chaotic systems are proposed. Firstly, a simple and efficient S-box method is introduced in order to use this S-box designed scheme in secure color image encryption technique. The major advantage of the proposed strategy is the dynamic aspect of keys used by chaotic map to generate strong S-boxes. Secondly, an efficient color encryption scheme based on chaotic maps and S-boxes in the form of permutation–substitution network is developed. Experimental results show the effectiveness of the proposed schemes. The suggested cryptosystems have superior performance and great potential for prominent prevalence in cryptographic applications compared to previous schemes.

A new chaos-based fast image encryption algorithm

Abstract: In recent years, various image encryption algorithms based on the permutation-diffusion architecture have been proposed where, however, permutation and diffusion are considered as two separate stages, both requiring image-scanning to obtain pixel values. If these two stages are combined, the duplicated scanning effort can be reduced and the encryption can be accelerated. In this paper, a fast image encryption algorithm with combined permutation and diffusion is proposed. First, the image is partitioned into blocks of pixels. Then, spatiotemporal chaos is employed to shuffle the blocks and, at the same time, to change the pixel values. Meanwhile, an efficient method for generating pseudorandom numbers from spatiotemporal chaos is suggested, which further increases the encryption speed. Theoretical analyses and computer simulations both confirm that the new algorithm has high security and is very fast for practical image encryption.

Image encryption using DNA complementary rule and chaotic maps

Abstract: This paper proposes a novel confusion and diffusion method for image encryption. One innovation is to confuse the pixels by transforming the nucleotide into its base pair for random times, the other is to generate the new keys according to the plain image and the common keys, which can make the initial conditions of the chaotic maps change automatically in every encryption process. For any size of the original grayscale image, after being permuted the rows and columns respectively by the arrays generated by piecewise linear chaotic map (PWLCM), each pixel of the original image is encoded into four nucleotides by the deoxyribonucleic acid (DNA) coding, then each nucleotide is transformed into its base pair for random time(s) using the complementary rule, the times is generated by Chebyshev maps. Experiment results and security analysis show that the scheme can not only achieve good encryption result, but also the key space is large enough to resist against common attacks.